Co Locus (Cocoa)
Gene involved: HPS3
 Inheritance: Autosomal recessive
 Mutation: chr23:43969695 (canFam3): G>A
Description:
The cocoa color in the French Bulldog corresponds to a specific dark brown shade caused by a mutation in the HPS3 gene, which is distinct from the classic chocolate brown associated with the B locus (TYRP1).
This mutation affects pigmentation of the coat, skin, and nose, and may sometimes be associated with green or amber eye color.
In the context of the cocoa color in the French Bulldog, a recent study demonstrated that the causative variant (HPS3:c.2420G>A) is strongly associated with the brown coat coloration. Although this variant affects the number of dense granules in platelets, no significant increase in bleeding tendency or health issues has been reported in homozygous dogs under normal breeding or everyday living conditions.
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